1. Field of the Invention
The present invention is directed towards a medical instrument of the type structured for use in laparoscopic and/or endoscopic surgery such as, but not limited to, a trocar assembly which includes an obturator having an elongated shaft with a penetrating tip formed on one end thereof. The penetrating tip includes an exterior surface configuration structured to facilitate the forming of an access opening in a patient's bodily tissue in a manner which requires a minimum application of an inwardly directed, linear pushing force on the instrument, but which nevertheless results in the dilation of body tissue. The configuration of the inventive penetrating tip is at least partially characterized by a perpendicular cross-section of the exterior surface having a substantially elliptical configuration along at least a majority of the tip.
2. Description of the Related Art
In the past when patients were in need of certain routine surgical operations, it was common for the medical doctor(s) to make a substantially large incision into, through and across the patient's abdominal cavity in order to reach the affected organ(s) and/or other body tissue. While the size of the incision made would vary dependent upon the type of surgery needed, for some surgeries it was relatively common to make a large incision, which would be closed using conventional techniques upon completion of the surgical procedure. However, the making of large incisions in the patient's body itself causes trauma and the period of time required for the patient to completely heal was and is significant. In addition, the pain or discomfort endured by the patient during the recuperative period was a serious problem.
Because of such disadvantages, new surgical procedures have been developed, as well as instruments utilized in the support of such procedures, which are widely used today. The most common and popular is laparoscopic and/or endoscopic surgery, wherein one or more small openings, utilizing appropriate penetrating instruments, are formed to provide access into the intended body cavities. A trocar assembly is typically used to create and maintain the small opening extending across the abdominal wall and into the body cavity and also to provide a channel through which instruments can be inserted and manipulated to perform the surgery inside the body cavity. As part of these procedures, the abdomen is inflated with an insufflation gas to maintain the abdomen in a distended state, and the trocar assembly usually carries one or more valves to form seal(s) to maintain insufflation. Laparscopic surgery has proven effective in greatly reducing the healing period for patients who have had to undergo surgery and have resulted in significantly less pain and discomfort to the patient.
The medical instruments used during laparoscopic surgery to form the one or more small access openings and during the surgery itself are commonly referred to as trocars or trocar assemblies. Typically, the trocar assembly includes a trocar having a housing and a sleeve or cannula and separately, an obturator which is slidably inserted into the trocar housing and cannula. In almost all cases, the obturator is formed to have a sharply pointed tip, usually defined by a multi-sided pyramide-like configuration, and serves as the penetrating instrument in that upon being inserted and positioned within the lumen of the cannula or trocar sleeve, the sharp pointed tip is exposed at the distal end of the trocar sleeve. The exposed sharpened tip of the obturator is forced into the patient's skin and through all of the various layers of body tissue with the trocar sleeve being forced through the perforation formed by the sharpened obturator tip. Typically, significant pressure must be applied once the peritoneum is reached, i.e., the toughened lining or membrane that defines the exterior wall of the body cavity, in order to penetrate through it and gain access to the body cavity and organs contained therein, in order that laparoscopic surgery may be performed. Once access to the body cavity is established, the obturator is typically withdrawn, leaving the trocar sleeve or cannula as a channel or access passage to the body cavity and intended organ. In some laparoscopic surgical techniques, the obturator or other sharp penetrating instrument may be used without a trocar, i.e., as a “stand alone” device to puncture through the skin and underlying bodily tissues. In such cases, it is understood that once a small access opening is formed, a separate access cannula, catheter or other surgical instrument is inserted into communication with the now accessed body cavity and/or organ.
While the design of trocars currently available on the market, and the obturators with their sharpened penetrating tips in particular, are capable of quickly forming the small access openings and channels into a patient's abdominal cavity, there are potentially serious drawbacks. Specifically, and as described briefly above, a significant amount of pressure—namely, an inwardly directed pushing force—must typically be applied to the trocar assembly in order to pierce through and penetrate the tough lining or membrane adjacent to and protecting the patient's body cavity and internal organs housed therein. Especially in forming the first access opening, where the surgeon does not have the benefit of observation via a camera instrument disposed within a trocar in a previously formed opening, the pressure applied to penetrate into the body cavity may momentarily result in the sharpened obturator tip extending too far into the cavity, such that an organ may inadvertently be nicked or scratched, without the surgeon's knowledge. If left untreated, such events can result in the rise of an infection and the patient may undergo serious complications, including the possibility of death or further surgery. Less significantly, the sharp pointed tips of the obturators can cause other damage, in terms of cutting small blood vessels and/or other delicate structures found within the body tissue surrounding the access opening during its formation.
To address this drawback, some in the art have endeavored to provide the trocar assembly with a protective shield, which in some cases, is intended to automatically move into a protective covering relation over the sharpened obturator tip once it has pierced into the abdominal cavity. Others have similarly noted this problem and attempted to provide the trocar with a sharpened tip that can automatically retract once it has penetrated the abdominal cavity or with some sort of visual signal to indicate that the empty space of the abdominal cavity has been reached. It is believed, however, that all such efforts have resulted in trocar assemblies that are overly complicated, difficult to implement and/or repair, and which may not reliably achieve the intended goal, especially in those situations where the surgeon is making the very first access opening and is unable to observe the body cavity with the aid of a small camera instrument.
Accordingly, there is a need in the medical field for an improved instrument which may be used independently, or more preferably, as part of a trocar assembly and/or associated components such as, but not limited to, a trocar sleeve, etc. to forming an access opening into a patient's body cavity in a manner which requires minimum application of an inwardly directed, linear pushing force. If any such improved instrument were developed, it should be structured to include a penetrating tip that facilitates clean formation of a small access opening extending through a patient's body tissue without severing blood vessels or causing similar damage to the outer tissues being penetrated. Ideally, any such improved instrument would have a penetrating tip that is cooperatively structured and configured relative to the distal end of the trocar sleeve so as to effectively enlarge the access opening, as the penetrating instrument is advanced there-through and into communicating relation with a predetermined body cavity, while simultaneously preventing pieces of the body tissue from entering into the internal passage of the trocar sleeve. Moreover, if any such improved instrument were developed, it should also be structured to allow for puncturing into the peritoneum or tough lining of the body cavity with little or no risk that an organ within the body cavity would be punctured or nicked.